The present invention relates in general to an injection molding technique, and in particular to a new and useful method of manufacturing a clear plastic product which has an evenly distributed dispersion of glitter particles within the volume of the product.
There are various ways of shaping plastic to form consumer products. Among these, one of the most versatile techniques is injection molding. Injection molding is used for many thermosetting compounds and for almost all thermal thermoplastic compounds with few exceptions. During injection molding, a granular plastic is heated and forced through a heated cylinder. The melted hot mass is then injected into a closed mold cavity. After cooling, the plastic part is removed.
When it is desired to make a product from transparent plastic and have the final product transparent, care must be taken to insure that the conditions to which the plastic is subjected do not render the plastic opaque.
One of the present inventors has already developed a cast product which is transparent plastic and which includes glitter particles in the body of the product. Since cast products have many serious limitations, including the fact that at least one surface of the product must be flat and the process is not particularly suited to making three dimensional shapes, the present inventors determined that injection molding would be a preferred technique for making plastic products. It was not clear, however, how the glitter particles could be dispersed evenly through the volume of the product or if, in fact, this was possible at all.